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18 Μαρ 2010 · This will show you any database links set up on the database: select * from dba_db_links; You would then have to search for any queries or objects using the db link by doing a text search of them for the link syntax <tablename>@<dblink name>
14 Νοε 2011 · These views are helpful for working with DB links in Oracle: DBA_DB_LINKS - All DB links defined in the database; ALL_DB_LINKS - All DB links the current user has access to; USER_DB_LINKS - All DB links owned by current user; See more in Oracle documentation
In this tutorial, you have learned about the Oracle database link concept and how to use the Oracle CREATE DATABASE LINK to create a new database link to a remote Oracle Database server.
This chapter describes SQL queries and subqueries. This chapter contains these sections: About Queries and Subqueries. Creating Simple Queries. Hierarchical Queries. The Set Operators. Sorting Query Results. Joins. Using Subqueries.
Hierarchical queries come with operators, pseudocolumns and functions to help make sense of the hierarchy. LEVEL : The position in the hierarchy of the current row in relation to the root node. CONNECT_BY_ROOT : Returns the root node(s) associated with the current row.
After you have created a database link, you can use it in SQL statements to refer to tables, views, and PL/SQL objects in the other database by appending @ dblink to the table, view, or PL/SQL object name. You can query a table or view in the other database with the SELECT statement.
FOREIGN KEY. The FOREIGN KEY constraint is a key used to link two tables together. A FOREIGN KEY is a field (or collection of fields) in one table that refers to the PRIMARY KEY in another table.
